A compendium of astronomy; containing the elements of the science, familiarly explained and illustrated, with the latest discoveries. Adapted to the use of schools and academies, and of the general reader (1850)
Olmsted, Denison, 1791-1859 · New York, R. B. Collins · leaf 67
y bedone either by a convex lens, or by a concave mirror. Aconvex lens is a flat piece of glass, having its two facesconvex, or spherical, as is seen in a common sun glass.Every one who has seen a sun glass, knows that whenheld towards the sun it collects the solar rays into asmall bright circle in… … the tube of a telescope. At the front end, or at the endwhich is directed towards the object, (which we willsuppose to be the moon,) is inserted a convex lens,L, which receives the rays of light from the moon, andcollects them into the focus at «, forming an image ofthe moon. This image is viewed…
Astronomy
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